better root ns

* ModuleDescrpiptor now lives in context
* ns parent is module descriptor iff ns is root ns
* minor test enhancements

compiler/backend/src/org/jetbrains/jet/codegen/JetTypeMapper.java

@@ -212,9 +212,12 @@ public class JetTypeMapper {
         if(name.contains("/"))
             return name;
         if (container != null) {
-            if (container instanceof ModuleDescriptor) {
+            if (container.getContainingDeclaration() instanceof ModuleDescriptor) {
                 return name;
             }
+            if (container instanceof ModuleDescriptor) {
+                throw new IllegalStateException("missed something");
+            }
             if(container instanceof JavaNamespaceDescriptor && JavaDescriptorResolver.JAVA_ROOT.equals(container.getName())) {
                 return name;
             }